Process of producing metallic alloys



QNITED STATES PATENT OFFICE.

W'ILLIAM l-I. GREENE AND WILLIAM H, WAHL, OF PHILADELPHIA,

' PENNSYLVANIA.

PROCESS OF PRODUCING METALLIC A LLOYS.

SPECIFICATION forming part of Letters Patent No. 490,961, dated January31, 1893.

Application filed July 2, 1892. e'rial No. 438,738. (No specimens.)

To all whom it may concern.-

Be it known that we, WILLIAM H. GREENE and WILLIAM H. WAHL, bothcitizens of the United States, and residents of Philadelphia,Pennsylvania, have invented a Process of Producing Metallic Alloys, ofwhich the following is a specification.

The object of our invention is to provide a cheap and efficient meansfor the production of certain metallic alloys, and our process consistssubstantially in utilizing metallic silicides, for the reduction ofcertain difficultly reducible oxides, or of such as cannot be reduced bymeans of carbon without the introduction of an objectionable quantity ofcarbon into the resulting metal.

The term metallic silicides as we use it, is intended to include allmetallic compounds or mixtures in which the element silicon is presentin such quantity as to justify their designation as siliciferous alloys,or siliconized alloys, terms which are well understood by metallurgists.It is not practicable in this definition to name a minimum quantity ofsilicon that would suit all cases, for the reason that silicon affectsthe physical properties of difierent metals differently, and what wouldbe a small proportion for one metal would be a large proportion foranother, and because the presence of other elements may profoundly alterthe properties of the alloy. Thus, in commercial cast iron theproportion of silicon may vary from a trace to about 3.5 per cent. as amaximum. Ordinary cast iron containing 3.5 per cent. of silicon We wouldtherefore not consider to be a silicide, but if an iron containing 3.5per cent. silicon at the same time contain a proportion of carbon, notexc'eeding one per cent, we would consider it for our purposes to be asilicide. Other metals than iron we consider to be silicides when theycontain two per cent. of silicon. When such silicides are heated withmetallic oxides in presence of a suitable base, such as lime, magnesiaor alumina, the oxygen of the oxide combines with the silicon formingsilica which at once unites with the base forming a fusible silicatethat separates as slag, while the metals set free then combine togetherforming an alloy. By suitable regulation of the proportions andcharacter of the silicide, metallic oxide and flux; or, by repeating theoperation of fusion with fresh additions of ore, or by the addition ofany given metal to the original charge or to the product of the firstre-action, we are enabled to produce metallic alloys or mixtures havingany required composition.

Our process, it will be observed, enables us to effect the reduction ofnumerous metallic oxides without the aid of carbon, a circumstance whichin certain cases especially in the manufacture of metals used in theproduction of certain special steels, is of vital importance. In fact,we wish to affirm in general terms that We effect the reduction ofmetallic oxides under entirely new conditions Which enable us to producewith advantage I not only well known and useful metallic alloys andcompositions, but also others heretofore unknown having new and valuableproperties. case of" manganese steel. By the present method ofmanufacturing this alloy, which consists in the addition of ordinaryferromanganese to fluid iron, the proportion of manganese that canusefully be introduced into the product is limited by the carbon whichto the amount of live to six per cent, is present in theferro-manganese, and which cannot be eliminated therefrom because of itsafiinity for manganese. By our process, we are able to produce an alloyof iron and manganese containing so small a proportion of carbon as topermit of the. introduction of a much larger proportion of manganeseinto steel than by the present method, withoutintroducing so much carbonas to overstep the permissible limit. It is evident that in all ouroperations, whether performed on the hearth of a furnace, or incrucibles, the presence in either, or in the flux, of free carbon, muststrictly be avoided. y

We will now describe our process in detail, taking as an example itsapplication to the mannfactu re of manganese steel. In this case weemploy the commercial products known under the names of ferro-silicon,silico-spiegel, and silico-ferro-manganese, which may be described assilicides of ironor of iron and manganese containing a variableproportion of silicon, usually from six to thirty per cent, and acomparatively low percentage of carbon.

As an example We will cite the Since, for reasons previously stated, inthe absence of carbon in notable proportion is of great'importance inmanganese steel, we employ for our purpose a silicide containing as hlgha proportion of silicon and as low a proportion of carbon as possible.Silicon irons and spiegels containing as much as fifteen .or twenty percent. of silicon, and with carbon not exceeding one per cent, canreadily be obtained, and by special selection of ores and fluxes can bemade even richer than this in silicon. As a rule, also, the quantity ofcarbon present in such silicides varies with the silicon in an inverseratio, carbon decreasing as silicon increases and vice versa. Asilicide, which may be either ferro-silicon or silico-spiegel ofsuitable composition having been selected, it is melted on the hearth ofa furnace having preferably a lime or magnesia lining, and when melted aquantity of the non-oxide or protosesqui-oxide of manganese (preferablythe former) with which there has previously been incorporated a quantityof any suitable flux, is added thereto. The reaction takes placepromptly, the silicon of the ferro-silicon seizes upon the oxygen of themanganese ore,and is thereby convertcdinto silicic oxide which formswith the flux a liquid slag, while the manganese set free by thereduction of the ore combines with the molten iron set free from thesilicide. Agitation of the charge will, of course, facilitate theoperation by bringing more quickly the ingredients of the charge intointimate contact. The whole charge of manganese ore and flux may beadded to the ferro-silicon at once, or the addition may be made byportions until a sufficient quantity of the oxide has been employed toutilize the reducing power ofall of the silicon that was present in theferrosilicon, thus reducinga chemically equivalent quantity of manganeseoxide to the metallic state.

Assuming that We operate with a silicide containing iron, eighty-eightper cent., silicon, ten per cent; carbon, one per cent.; as the reactionwill take place according to the equation we employ silicide andmanganese oxide in quantities that satisfy the above proportions, t'. e.for every twenty-eight parts of silico'nin the silicide, one hundred andforty-two parts of manganese monoxide are added, and the quantity oflime, magnesia, or alumina or a mixture of these, that will completelycombine-with the silica to form a fusible silicate.

We have found it necessary to use a larger quantity of manganese orethan that required by theory, for the reason that a certain quantity ofthe manganese oxide is always seized upon by the silica and passes intothe slag in the form of manganese silicate. We have found the followingproportions by weight of charge to yield good results:--ferro-siliconcontaining ten per cent. silicon one per cent.

carbon one hundred pounds. Manganese monoxide, seventy pounds. Lime,fifty pounds. A charge of this composition will yield about one hundredand twenty-eight pounds of a metallic alloy having this composition:iron tion iron 78.8 manganese 20.7 carbon 0.5 silicon trace.

In the preparation of a manganese steel containing the same percentageof carbon by melting decarburized iron with ordinary ferro-manganesecontaining eighty per cent. manganese and 5.5 per cent. carbon, theresulting metal would contain 92.23 per cent. iron and only 7.27 percent. manganese. Or, making the comparison on the basis of equivalentquantities of manganese, the manganese steel -made from the ordinaryferro-manganese would contain for 20.7 per cent. manganese 1.4 per cent.carbon: that made by our process would contain for 7.27 per cent.manganese only 0.18 per cent. carbon. 7

By strictly analogous methods of operation, other special steels oralloys of iron may be formed, thus the substitution of tungstic oxidefor the manganese oxide in the previously described operation willresult in the formation of an alloy of iron and tungsten applicable tothe manufacture of tungsten steel.

In many cases, it is obvious that a metal of the desired composition maybe obtained directly by one operation on the furnace hearth.

Thus for the production of a manganese steel of a given composition therequired propor tions of scrap Wrought iron and ferro-silicon of asuitable composition may be melted on the hearth, in contact with themanganese oxide.

In the manner described, alloys of copper with difficult reduciblemetals may be obtained by fusing appropriate oxides with coppersilicide, and other silicides will doubtless be found useful for similarpurposes.

We are aware that in the manufacture of steel by what is commonly knownas the open hearth process, pig iron and scrap, containing a small andvarying proportion of silicon, are melted in contact with oxides ofiron, and that the chemical reaction which takes placein this Ioperation is similar to that which occurs in the operation of ourprocess. The carbon and silicon of the iron, both of which, butessentially the first, it is the object of the open hearth steel processto remove, are burned out by the oxygen of the iron ores. But with thesimilarity of the chemical reactions the analogy between our process andthe open hearth steel process ceases.

In the open hearth, the process is essentially IIO one ofdecarburization, and the separation of the small quantity of siliconfrom the pig iron contain but little silicon are preferred, and

its total absence does not in the least affect the operation of theprocess. I

In the open hearth process the silicon of the cast iron is an accidentaland objectionable constituent which it is desirable to remove. On thecontrary, for our purpose the silicon is absolutely essential, and thehigher its percentage the more efficient does our process become.

We are also aware that in the commercial reduction, remelting, andcasting of many metals and alloys it is difficult or impossible toprevent the retention or the formation of small quantities of oxide, andthe absorption of certain gases, such as carbonic oxide and atmosphericoxygen by the metals, and that the presence of even very minutequantities of such oxide and occluded gases has a very unfavorableinfluence on the strength, ductibility, and other desirable qualities ofthe metal, and renders it extremely troublesome to rollor obtaincastings free from blow-holes. Thesedifficulties are due to the factthat the presence of slight quantities of oxides and occluded gasesprevents the intimate coalescence of the particles of the metal and theproduction of a perfectly homogeneous text ure. And we are aware that ithas long been the practice to counteract the deleterious influencesabove named by subjecting the metal prior to its withdrawal from thefurnace, or cupola, or crucible, or in the ladle just before pouringinto the mold, to a species of purification or refiningin which theobjectionable traces of oxides or harmful occluded gases are removed bythe addition to the reduced or remelted metal or alloy while in themolten state of minute quantities of some powerful deoxidizing agent.For the purpose of such purification or refining, phosphorus, manganese,aluminum, magnesium, and silicon are more or less commonly used,sometimes in the form of compounds or alloys, and sometimes in theelementary form. As examples, we cite the addition of phosphorus insmall quantity, generally in the form of phosphorcopper, or phosphor-tinto copper, brass and bronze, to burn out the traces of cuprous oxide andmake a stronger and tougher metal or alloy; the addition of minutequantities of metallic magnesiumto metallic nickel to remove occludedcarbonic oxide; of small quantities of term-manganese, orferro-silicon,-to molten steel in the open hearth process at the closeof the melting, and of copper, tin, and zinc silicides to metalliccopper, tin, and zinc, for the same general purpose, to insure theproduction of homogeneous metal and sound castings.

These operations,

though depending on the general principle of chemical reduction are notcomparable with our invention which differs radically in the objectattained, in the mode of procedure, and in the scope of its application.The

silicides,-in the cases above referred to, are

added to metals previously reduced by agents other than silicon, and areused in a finishing operation for the purpose of removing small andgenerally minute quantities of certain objectionable impuritiesunavoidably contracted in the previous operation of .reduction bycarbon, or in the remelting, and if they are added in quantities greaterthan may be required for the purification of the the metals, this isdone for the purpose of forming a silicon alloy, which is foreign to thepurpose of our invention.

Our process relates exclusively to the reduction of oxidized ores ofmetals by bringing such oxides in proper proportion in contact withmetallic siiicides, and effecting the reduction of the ores solely bythe silicon of the silicides with the aid of heat. This metallurgicaloperation which we have devised, differs substantially and radicallyfrom the above described operation of purification of metalscontaminated with small quantities of oxide or by occluded gasesacquired in the process of their reduction by carbon, or in theremelting; and, we accordingly disclaim such uses of metallic silicidesas being foreign to the purpose of our invention.

We claim as our invention:

1. In the art of manufacturing metallic alloys, the herein describedprocess which con- 2. In the art of manufacturing metallic alloys, theherein described process which consists in heating to a suitabletemperature in WILLIAM H. GREENE. WILLIAM H. WAHL.

WVitnesses:

HENRY HowsoN, HARRY SMITH.

